The present invention relates to a liquid waste disposal system for aircraft which have a pressurized passenger compartment.
In a typical passenger aircraft having toilet and lavatory facilities, the waste from the toilet is stored in a tank, while the lavatory sink waste water is vented through an aft drain mast line of the airplane. The reason for this, of course, is that keeping the total weight carried by the aircraft at a minimum is a very important consideration, and a discharge of waste sink water into ambient atmosphere during flight is not objectionable.
However, this arrangement offers certain disadvantages during onground aircraft operation. During loading of passengers through an aft stairway of the aircraft on windy days, there is a possibility that passengers may be sprayed with waste water if the lavatory sink is used at that time. Also, sink waste water discharged from the aircraft could freeze and create ice on airport aprons and runways.
To solve this problem, some years ago it was suggested that a device be installed to divert all sink waste water to the toilet tank during onground operations, and to the drain mast line during inflight operation. Accordingly, a system has been installed in some aircraft where a line leading from the lavatory sink at a certain location branches into two lines, one leading to the toilet storage tank, and the other to the drainmast line. To divert the water to the drain mast line during flight, pressurized air is directed through the lavatory sink vent line. Because of the pressure differential between the aircraft cabin and the ambient atmosphere, the air passing through the vent line in a sense forces the water through the drainmast line and not to the toilet tank which is pressurized to a level above ambient pressure. However, this arrangement has not been totally satisfactory in that during flight a portion of the sink waste water still flows into the toilet tank, and with the aircraft on the ground, some of the water still is diverted into the drain mast line.
In a search of the U.S. Patent literature, a number of prior patents were disclosed. While these are not considered to be particularly relevant to the present invention, these are disclosed herein to insure that the applicant is complying with his obligation to disclose all prior art of any possible relevance to the U.S. Patent and Trademark office. These patents are as follows.
U.S. Pat. No. Re. 27,087, Binder, relates to a proportional fluid amplifier which diverts a proportion of liquid flow between separate outlet passages in response to the flow on a controlling fluid through the amplifier.
U.S. Pat. No. 700,719, Allen et al., discloses a waste disposal system for a railroad car, where there is a mechanical system for discharging the waste to an outside location, or placing the waste in a holding tank.
U.S. Pat. No. 1,227,232, McGary et al, discloses a particular toilet configuration with a holding tank.
U.S. Pat. No. 1,711,235 shows a waste disposal system adapted to be mounted in an automobile, and having a holding tank.
U.S. Pat. No. 1,996,325, Cox, shows a system where toilet waste is treated with a sterilizing agent.
U.S. Pat. No. 2,119,328, Haberlin, discloses a vehicle toilet system in which wash basin water is temporarily held for subsequent use as toilet flushing water which may be exhausted to the open atmosphere or into a holding tank.
U.S. Pat. No. 2,565,720, Collison et al, discloses a system for treating waste by means of engine exhaust.
U.S. Pat. No. 3,406,951 shows a particular arrangement of a fluid amplifier for use in a fuel system.
U.S. Pat. No. 3,477,699, Drayer, shows a fluidic device for use in a fuel system.
U.S. Pat. No. 3,833,943, Sturtevant, discloses a disposal system for use in conjunction with a high temperature heat source in which waste material is mascerated and discharged into the source of heat.
U.S. Pat. No. 3,936,888, Sturtevant, discloses a system generally similar to the Sturtevant patent noted above.